<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
<head>
   <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
   <meta name="Author" content="Ralph Grishman">
   <meta name="GENERATOR" content="Mozilla/4.7 [en]C-CCK-MCD NSCPCD47  (Win95; I) [Netscape]">
   <title>Reference Resolution</title>
</head>
<body text="#000000" bgcolor="#FFF0F0" link="#FF0000" vlink="#800080" alink="#0000FF">

<h2>
<font face="Arial Alternative"><font color="#3333FF">Reference Resolution</font></font></h2>
The Jet reference resolver resolves anaphoric references to noun phrases.&nbsp;
It is intended to be invoked as the last step in processing each sentence
in a document.
<p>The input to reference resolution consists of a set of annotations of
type <b>constit</b> with <b>type=ngroup</b>.&nbsp; These are called the
'mentions'.&nbsp;&nbsp; Each such annotation should have a <b>pa</b> feature
giving its predicate-argument structure, and -- if its head is a name --
the feature <b>isName</b> with some non-null value.
<p>The output of reference resolution is a set of annotations of type <b>entity</b>.&nbsp;
Each <b>entity</b> annotation corresponds to a set of one or more mentions
which are deemed to be coreferential.&nbsp; The <b>entity</b> annotation
has the features <b>head</b>, <b>position</b>, <b>mentions</b>, <b>number</b>,
<b>name</b>,
and <b>human</b>.
<p>Mentions are resolved as follows:
<ul>
<li>
a common noun mention is resolved with the closest prior mention with the
same head, or with a head which is associated with the same concept or
a more specific concept in the concept hierarchy</li>

<li>
a name mention is resolved with the closest prior mention with the same
name, or a superstring of the current name (so that, for example, "Bush"
will be resolved with "George Bush")</li>

<li>
a third-person pronoun mention ("he", "she", "it", "they", "him", "her",
"them") will be resolved with the closest prior mention which agrees with
the pronoun in number and human-ness (antecedents of "he", "she", "him",
and "her" must be human;&nbsp; antecedents of "it" must not be human).&nbsp;
Human-ness for nouns is based on the <b>human</b> feature in the predicate-argument
structure;&nbsp; for names, <i>person</i> names are considered human, while
other names are considered non-human.&nbsp; This classification is slightly
incorrect since the dictionary labels an entry as human if any sense (not
necessarily the most common sense) of that entry is human.</li>

<li>
a first- or second- person pronoun is resolved with the closest prior mention
of the same pronoun</li>
</ul>
If no prior mention satisfies the given constraints, a new entity is created.
<p>In addition, after mentions are resolved, reference resolution searches
for annotations of type <b>event</b>.&nbsp; For each <b>event</b>, it generates
an annotation of type <b>r-event</b> which is identical except that any
feature whose value is a mention (<b>ngroup</b>) is replaced by the <b>entity</b>
to which the mention was resolved.
<br>&nbsp;
<br>&nbsp;
</body>
</html>
